Method for operating a fuel cell, and fuel cell system

Abstract

A method for operating a fuel cell. The fuel cell is supplied with gaseous fuel via an anode-side gas feed line and with air via a cathode-side gas feed line. The anode-side gas feed line and the cathode-side gas feed line are coupled via a pressure-transmitting element, wherein in the event of an increased power requirement of the fuel cell, the gas pressure of the anode-side gas feed line is at least partly transmitted to the cathode-side gas feed line via the pressure-transmitting element and causes the gas pressure of the cathode-side gas feed line to increase. A fuel cell system having at least one fuel cell, an anode-side gas feed line, a cathode-side gas feed line, and a monitoring unit.

1 . A method for operating a fuel cell comprising: supplying gaseous fuel to the fuel cell via a gas feed line on an anode side and supplying air via a gas feed line on a cathode side; coupling the anode-side gas feed line and the cathode-side gas feed line via a pressure-transmitting element; and in the event of an increased power requirement for the fuel cell, at least partially transmitting a gas pressure from the gas feed line on the anode-side via the pressure-transmitting element to the gas feed line on the cathode-side to cause an increase in a gas pressure of the cathode-side gas feed line. 
     
     
         2 . The method according to  claim 1 , wherein the pressure-transmitting element has a flexible membrane or a displaceable piston. 
     
     
         3 . The method according to  claim 1 , further comprising admitting compressed air from a pressure accumulator to increase the gas pressure of the gas feed line on the cathode side. 
     
     
         4 . The method according to  claim 3 , further comprising refilling the pressure accumulator after the increased power requirement has ended until a target pressure of the pressure accumulator is reached, wherein an air pressure of the pressure accumulator is increased in stages up to the target pressure. 
     
     
         5 . The method according to  claim 1 , wherein the anode-side gas feed line has a high-pressure section and a low-pressure section, wherein the pressure-transmitting element is connected to the high-pressure section by a first valve and to the low-pressure section by a second valve, the method further comprising opening the first valve and closing the second valve to transmit the gas pressure from the anode-side gas feed line to the cathode-side gas feed line. 
     
     
         6 . The method according to  claim 5 , further comprising, after the gas pressure of the anode-side gas has been transmitted to the cathode-side gas feed line, closing the first valve and opening the second valve to supply gaseous fuel from one section between the first and second valve through the second valve of the fuel cell. 
     
     
         7 . The method according to  claim 3 , further comprising refilling the pressure accumulator by at least partially transmitting the gas pressure of the anode-side gas feed line to the pressure accumulator by the pressure-transmitting element, wherein the cathode-side gas feed line has an accumulator section which is connected to the pressure-transmitting element via a third valve, is connected to the fuel cell via a fourth valve, and is connected via a fifth valve to the pressure accumulator, wherein the fourth valve is closed and the fifth valve is opened to refill the pressure accumulator in a first filling step with the third valve open, wherein the gas pressure of the anode-side gas feed line is at least partially transmitted to the accumulator by the pressure-transmitting element via the accumulator section, whereby the fourth valve is opened and the fifth valve is closed in a second filling step. 
     
     
         8 . The method according to  claim 7 , further comprising, after the pressure accumulator has been refilled, closing the third valve and opening the fifth valve to admit compressed air from the pressure accumulator. 
     
     
         9 . The method according to  claim 1 , further comprising pressurizing the air in the cathode-side gas feed line with a compressor, wherein an operation of the compressor with an increased compressor power causes a further additional increase in the gas pressure of the cathode-side gas feed line. 
     
     
         10 . The method according to  claim 1 , wherein an air pressure at an inlet of the fuel cell is limited by a pressure regulator or a self-regulating element. 
     
     
         11 . A fuel cell system comprising: at least one polymer electrolyte membrane fuel cell, an anode-side gas feed line a cathode-side gas feed line, and a control unit, wherein a pressure-transmitting element is arranged between the anode-side and the cathode-side gas feed lines, wherein the control unit is configured to at least partially transmit a gas pressure from the anode-side gas feed line via the pressure-transmitting element o the cathode-side gas feed line in the event of an increased power requirement for the fuel cell to cause an increase in a gas pressure of the cathode-side gas feed line. 
     
     
         12 . The fuel cell system according to  claim 11 , wherein the fuel cell system has a pressure accumulator, and in the event of the increased power requirement, the control unit is configured to cause an additional increase in the gas pressure of the cathode-side gas feed line by admitting compressed air from a pressure accumulator. 
     
     
         13 . The fuel cell system according to  claim 12 , wherein the pressure-transmitting element has a flexible membrane or a displaceable piston. 
     
     
         14 . The fuel cell system according to  claim 12 , wherein the control unit is configured to refill the pressure accumulator after the increased power requirement has ended until a target pressure of the pressure accumulator is reached. 
     
     
         15 . The fuel cell system according to  claim 12 , wherein the anode-side gas feed line has a high-pressure section and a low-pressure section, wherein the pressure-transmitting element is connected to the high-pressure section by a first valve and to the low-pressure section by a second valve, and wherein the control unit is configured to open the first valve and close the second valve to transmit the gas pressure from the anode-side gas feed line to the cathode-side gas feed line. 
     
     
         16 . The fuel cell system according to  claim 15 , wherein the control unit is configured to, after the gas pressure of the anode-side gas has been transmitted to the cathode-side gas feed line, close the first valve and open the second valve to supply gaseous fuel from one section between the first and second valve through the second valve of the fuel cell. 
     
     
         17 . The fuel cell system according to  claim 12 , wherein the cathode-side gas feed line has an accumulator section which is connected to the pressure-transmitting element via a third valve, is connected to the fuel cell via a fourth valve, and is connected via a fifth valve to the pressure accumulator, wherein the control unit is configured: to refill the pressure accumulator by at least partially transmitting the gas pressure of the anode-side gas feed line to the pressure accumulator by the pressure-transmitting element, close the fourth valve and open the fifth valve to refill the pressure accumulator in a first filling step with the third valve open, at least partially transmit the gas pressure of the anode-side gas feed line to the accumulator by the pressure-transmitting element via the accumulator section, and open the fourth valve and close the fifth valve in a second filling step. 
     
     
         18 . The fuel cell system according to  claim 17 , wherein the control unit is configured to, after the pressure accumulator has been refilled, close the third valve and open the fifth valve to admit compressed air from the pressure accumulator. 
     
     
         19 . The fuel cell system according to  claim 12 , further comprising a compressor for pressurizing the air in the cathode-side gas feed line. 
     
     
         20 . The fuel cell system according to  claim 12 , further comprising a pressure regulator or a self-regulating element for limiting an air pressure at an inlet of the fuel cell.